Flanged pipes with low clamping stress



July 25, 1967 w. R. DOTY FLANGED PIPES WITH LOW CLAMPING STRESS OriginalFiled Nov. 18, 1965 INVENTOR WILLIAM R. 007') BY fynsl @L ,fl m TORNEYSUnited States atent 3,332,710 FLANGED PIPES WITH LOW CLAMPING STRESSWilliam Russell Duty, Oakland, Calif., assignor to Chevron ResearchCompany, a corporation of Delaware Continuation of application Ser. No.324,294, Nov. 18, 1963. This application Aug. 3, 1966, Ser. No. 570,088

7 Claims. (Cl. 285336) This application is a continuation of Ser. No.324,294, filed Nov. 18, 1963, and now abandoned.

This invention relates to glassware pipe used in chemical laboratoriesand more particularly to a fluid-tight joint formed between sections ofsuch pipe.

In my article (O-ring Seal-s for Glass Apparatus, Review of ScientificInstruments, volume 30, November 1959, pp. 1053-1054), there isdisclosed a joint for sealing flange ends of glass pipe incorporating aresilient O-ring. In the article, it is disclosed that pressure isapplied to the ends of the pipe to deform the O-ring by a clamp havingtwo U-shaped support rings connected to the backsides of the flangedends. In applying pressure to the O-ring, bolts are shown connected nearthe periphery of the rings to draw the flanged ends of the pipes intocontact with the O-ring.

Experience has shown that, owing to the shape of the clamp, the seal atthe unsupported segments of the O-ring (between the legs of the U-shapedsupport rings) is subject to less pressure than is generated at thesupported portions. Thus in some instances, for example, as vibration ofthe piping system occurs, the pressure at these segments may be toosmall to prevent leakage. On the other hand, if the bolt tension isincreased to assure an adequate sealing at all points around thecircumference of the O-ring, pressure near the tensioned bolts may bendthe flanges beyond their yield point. Furthermore, the flangesincorporated in the joint are often not flat along the surfaces engagingthe clamp. Thus, since high spots create stress concentrations that maybe greater than the yield point of glass, each surface must be carefullychecked before pressure is applied.

It is the object of the present invention to provide a jointincorporating an O-ring packing element designed to form a fluid-tightseal between the flanged ends of a pair of glassware pipe sectionswhere: (l) the joint is assembled and dismantled easily and quickly, (2)the joint is formed in a low cost manner without using lubricatingmaterials of any type, and (3) the bendingstresses acting at the ends ofthe pipes are reduced.

In accordance with the present invention, a fluid-tight quick-releasejoint is provided between the flanged ends of a pair of glass pipesections by establishing a fastreacting quick-release deforming pressureon an O-ring packing element located in grooves at the ends of thesections. A deforming pressure is established by a quickrelease clampthat includes (1) a pair of annular support members having insidediameters larger than the sections but smaller than the flanges, (2)L-shaped rubber cushions attached to the support members in contact withthe backsides of the flanges, and (3) a series of circumferentiallyspaced bolts that extend longitudinallly through openings in the supportmembers and press the cushions to the flanges. As the bolts aretightened, the tendency of the support members to bend at the peripheryof the flanges is restrained by the rubber cushions that increase therigidity of the clamp. The transverse lip of the cushions also reducesthe longitudinal component of force acting at the flange periphery andthe longitudinal bending stress acting at the attaching surfaces of theflanges and pipes.

Easy assembly and dismantling of the joint is achieved by constructingthe support members in approximate half a EQQ sections in which the endsof the halves overlap and are joined by diametrically opposed bolts.Open ended slots are formed in one section so that pivoting the supportmembers about the bolt located diametrically opposed to the slots breaksthe clamp away from the pipes. To aid further in dismantling the joint,compression springs are located in contact with the support members.Each spring is supported by and concentric of a bolt and providesmovement of the support members relative to the flanges as the bolts areloosened.

The present invention will become more apparent from the followingdetailed description of the invention taken in conjunction with thefollowing drawings in which:

FIGURE 1 is a side elevational view of a pair of pipe sections sealedtogether in a fluid-tight seal by a clamp embodying the invention;

FIGURE 2 is an enlarged transverse section taken along line II-II ofFIGURE 1 to illustrate the supports of the clamp;

FIGURE 3 is a longitudinal transverse section taken along line IIIIII ofFIGURE 2 in which the packing element, the flanged ends, and thesupports of the clamp are illustrated;

FIGURE 4 is a transverse sectional view of FIGURE 1 taken along lineIVIV in which segments of the supports of the clamp are folded awayillustrating connection of the clamp to the flanged ends of the pipe;and

FIGURE 5 is a side elevational view, partially cut away, of analternative embodiment of the invention in which resilient bumpers aresupported between the flanged ends and the support members of the clamp.

Referring to the drawings, particularly to FIGURES 1 and 3, aquick-release joint 2, constructed in accordance with the invention,used an O-ring packing element 3 to join flanged ends 8 and 9 of pipesections 4 and 5 in a fluid-tight and/or vacuum-tight seal. Toillustrate the fluid sealing aspect-s of the invention, the pipesections 4 and 5 are shown conveying the fluid in the direction ofarrows 6 and 7. This fluid may be a highly permeable gas such ashydrogen or a liquid having similar characteristics. The O-ring packeris of conventional design (circular cross section) and is seated inannular grooves 11 (FIGURE 3) formed in the flanged ends 8 and 9 of thepipes. These grooves lie adjacent coextensive alignment to form theO-ring capture chamber therebetween. The method of forming the glasstype to provide flanged ends 8 and 9 and grooves 11 is taught in mycopending application (Ser. No. 309,668, entitled Flange Forming Fixtureand Method, filed Sept. 8, 1963).

Using O-ring packers allows the joining of the pipe sections withoutusing lubricants, but to economically form fluid-tight seals, it isimportant:

(1) That adequate sealing pressure be applied at all points about thepacker,

(2) That the clamp allow quick assembly and dismantling of the pipejoint, and

(3) That the joint reduce the bending stress acting on the pipe as theclamp applies pressure at the packer.

Referring to FIGURES 1, 2 and 3 in accordance with the presentinvention, pressure of equal magnitude and direction is applied toO-ring packer 3 supported between flanged ends 8 and 9 of pipe sections4 and 5 by a quick-release clamp comprising annular support members 13and 14 positioned at the backsides of the flanged ends 8 and 9,resilient cushions 15 and 16 attached to the support members, andcircumferentially spaced bolts 17a, 17b, 17c and 17d extending throughopenings 18 in support members.

To assure that the pressure is circumferentially applied, bolts 17a-17dsqueezing the packer against annular grooves 11, are alsocircumferentially located about a circle whose axis lies on axis A.Since bending stress develops at the junction of flanged ends 8 and 9and sides 21 of the pipes directly relative to the radius of the boltcircle, the bolts are positioned as close as possible to the pipes. Thebolts are tensioned by means of wing unts 19 located at the backsurfaces of support member 14. As the distance between the bolt headsand the wing nuts is reduced, the flanged ends of the pipes are drawntogether to deform the packer.

Openings 18 are formed in the support members equidistant from axis A ofthe assembly and accommodate the bolts 17a17d. The openings are ofcircular cross section with the exception of the openings thataccommodate bolt 17a. As shown in FIGURE 4, the openings for bolt 17aare slotted, have arcuate side surfaces 28 and have radii centered ataxis A.

Support members 13 and 14 are concentric with axis A of the assembly andhave an inside diameter greater than that of the sides 21 of the pipesbut less than that of the flanges. The mean diameter (D) of thesemembers (FIGURE 1) is selected so that the clamp may be used to sealseveral sizes of pipe. This is achieved by selecting a flange meandiameter (d) that can be used with a given series of pipe sizes withoutforming bending stresses that will be beyond the yield point of theglass. Each support member is formed of pairs of crescent shapedsegments 13a, 13b, 14a and 1411, respectively as shown in FIGURES 2 and4. These segments have overlapping ends joined together by diametricallyopposed bolts 17a and 170. The bisegmented construction of the supportmembers allows the clamp to open at the junctions 26 and 27 of thesegments by releasing the pressure at bolt 17a and pivoting the segmentsabout an axis passing through bolt 170 as shown in phantom line inFIGURE 4.

The arc length (8) of the overlap section of the segments (FIGURE 4) isbisected by a plane that passes through axis A and bolt 17a and bolt 17cand relates to diameter of the support member in accordance with S=Dcos-1% where: D is the outside diameter of the support members, R is theoutside radius, and C is the cord connecting the central axis A with acord describing the end points of the overlapped sections. In practicethe arc length is approximately 1 inch for a support member of 3 /2inches outside diameter.

To allow pressure on the flanges to emanate from a common plane normalto the axis of the assembly, the

overlap sections of segments 13a and 14a are offset by steps 20 and 22as shown in FIGURES 2 and 4. The height of each step is approximatelyequal to that of the thickness of the segments to align the members,with the exception of the overlap sections, along a common plane.

However, the pressure produced at the support members by tighteningbolts 17a-17d is not transferred directly to the flanges. Resilientcushions '15 and 16, preferably rubber, have an annular configurationand attach to the support members to transfer the bolt pressure to theflanged ends. To assure that the bolt pressure is transferred to theflanges with minimum creation of bending stress, the transverse legs 23of the cushions have a radial width dimension suflicient to position theend of the leg at least at a radius equal to that of the grooves 11 and12 as shown in FIGURE 3. Longitudinal legs 24 of the cushions may bepositioned at the periphery of the flanges as shown to increase therigidity of the cushion relative to that of the support members. Thus asthe members are drawn together, the natural tendency of the members tobend as the bolts are tightened and increase the pressure at theperiphery (and hence .the bending stress) is reduced by the increasedlongitudinal area of the cushions. Additionally leg 24 also preventsradial movement of the flanges as vibration of the pipes occurs becausethe junction of legs 23 and 24 is located at the corners of the flanges.

To allow the cushions to follow pivotal movement of the support member,each cushion is formed in two crescent shaped segments. The ends of thesegments are located at points adjacent to the respective steps 29 and22 of the overlap end portions of the support members. The segmentsattach to the support members by means of an adhesive.

In dismantling the joint, the clamp 10 is easily removed from contactwith the flanged ends of the pipes with the aid of springs 25 sandwichedbetween the support members 13 and 14. Each spring is supported by abolt prior to scaling the pipes and, as the bolts 17a- 1'7d aretightened, is compressed. When the bolts are loosened, the compressionforce of the springs breaks any adhesive barriers developed at thesurfaces of the cushion and flanges during the time the seal is formed.Dismantling is aided further by the split construction of the supportmembers 13 and 14 and the cushions 15 and 16 previously mentioned. Thistype of construction allows the segments 13a and 14a to be pivoted aboutbolt 17c diametrically opposed to bolt 17a by merely releasing the bolttension on bolt 17a. The slots in these segments release the clampwithout the operator having to completely remove the wing nut attachedto bolt 17a.

Referring now to FIGURE 5, an alternative form of the invention isillustrated for sealing flanges in which resilient bumper elements 30,preferably rubber having a circular cross section, (i.e., an O-ringconfiguration) are positioned at the backsides of flanged ends 8 and 9to join pipe sections 4 and 5 in a fluid-tight and vacuum-tight seal. Asdistinguished from the embodiment shown in FIGURES l-4, the bumperelements 30 are not attached to the support members but are held incontact with the flanged ends by friction supplied to the members bybolts 17a17d. Prior to being squeezed by the support members, thebumpers are held in position opposite O-ring packer 3 by grooves 31 onthe flanged ends of the pipes as shown; by detents on the supportmembers, not shown; or by a hand tool having long fingers thatareslipped between the flanged ends of the pipe and the support members,not shown. The bumpers are preferably the same diameter and shape as theO-ring packer 3 seated between the flanged ends of the pipe. A commonsize of O-ring thus can be stocked for use of both forming the seal aswell as effectively distributing the sealing pressure over the pipes andresults in a considerable saving of time and cflt'ort since hundreds ofO-n'ngs may be used in a single day to seal glass piping in thelaboratory. But it should be noted that the shape of the bumpers can bechanged to meet changing operating conditions. For example, if shearingof the flanged ends of the pipe is a serious problem, the cross sectionof the bumpers may be changed from circular to rectangular to increasethe contact area between the bumpers and flanges, or to L-shaped toreduce the longitudinal component of force acting on the flanges inaccordance with the cushions of FIGURES l-4.

As the bolts 17a-17d are tensioned, pressure applied to the supportmembers is transferred to the bumper elements causing their deformationinto tight grippage with the grooves 31 in the flanged ends of thepipes. In turn, the pressure is transferred to the packer 3 as theflanged ends are moved toward one another, to seal the pipes in afluid-tight seal. It should be noted that, although it is desirable thatthe packer 3 and bumpers 30 have identical shape and size, the bendingstress at the junction of the flanged ends and sides 21 of the pipe, isdirectly related to radius of the bumpers 30. Thus, where the size ofthe pipes is small compared to the flanged ends, it may be necessary touse bumpers of smaller diameter than that of the packer.

In disassembling the joint, the clamp is aided in its removal fromcontact with the flanged ends by springs 25 sandwiched between thesupport members 13 and 14. Each spring is supported by a bolt prior tothe time the bolts are tensioned. As the bolts are loosened to dismantlethe joint each spring forces the support members to move away from eachother so that adhesive barriers at the surface of the bumpers and theflanged ends are broken.

The split construction of the support members allows respective segmentsof the support members to be pivoted about bolt 17c to remove the clampfrom contact with the flanges, as explained above. However, the bumpersare preferably a single piece construction for ease ofinterchangeability with O-ring packers 3 and are not permanentlyattached to the support members. The bumpers are inserted about andremoved from the pipes by simply stretching them over the flanged endsof the pipes. This may be done whether the bumper has a circular,rectangular, or L-shaped cross section. Slots are formed in the segmentsof the members in the manner of FIGURE 4 to allow the clamp to be openedwithout necessity of the operator to completely remove the wing nut frombolt 17a.

While certain preferred embodiments of the invention have beenspecifically disclosed, it should be understood that the invention isnot limited thereto, as many variations will be readily apparent tothose skilled in the art. The invention is to be given as broad aspossible an inter pretation within the limits of the following claims:

I claim:

1. A joint for releasably joining glassware members in fluid-tightcontact, comprising a pair of glassware sections having adjacent flangedends, said flanged ends having interior adjacent faces provided withgrooves, and outer faces remote from said interior faces, a gasket ofresilient material confined in said grooves, a releasable clamp toreleasably confine said gasket in said grooves under substantiallyuniform circumferential pressure, said clamp including a pair of supportmembers axially spaced apart adjacent to said outer faces of saidflanged ends, connecting means operatively engaged between said supportmembers for axially urging said support members into contact with saidouter faces of said flanged ends to confine said gasket, and a pair ofresilient cushions coaxial of said gasket, each of which connectingbetween one of said pair of support members and said outer face of oneof said flanged ends and having a mean diameter about equal to that ofsaid gasket for distributing said axial urging pressure incircumferential alignment with said gasket whereby bending stresses nearthe attaching plane of said flanged ends of said glassware sections arereduced.

2. Said joint of claim 1 in which said outer faces of said flanged endsin contact with said cushions are substantially normal to the axis ofsymmetry of said glassware sections.

3. The joint of claim 2 in which said cushions contacting with saidouter faces of said flanged ends of said glassware sections are annularand have circular cross sections.

4. The joint of claim 2 in which said cushions contacting said flangedends of said glassware sections have rectangular cross sections.

5. Said joint of claim 2 including spring means for moving said supportmembers in respective opposed directions as pressure is removed fromsaid gasket to effect release of said cushions from said glasswaresections, as said urging pressure is removed.

6. A joint for releasably joining glassware members in fluid-tightcontact, comprising a pair of glassware sections having adjacent flangedends, said flanged ends having interior adjacent faces provided withgrooves, and outer faces remote from said interior faces substantiallynormal to the axis of symmetry of said sections, a gasket of resilientmaterial confined in said grooves, a releasable clamp to releasablyconfine said gasket in said grooves under substantially uniformcircumferential pressure, said clamp including a pair of support membersaxially spaced apart adjacent to said outer faces of said flanged ends,each of said support members formed of at least two crescent-shapedsegments having at least first and second overlapping end sections withopenings therethrough, a series of nut-and-bolt assemblies operativelyengaged through said openings capable of axially urging said supportmembers into contact with said outer faces of said flanged ends toconfine said gasket, a pair of resilient cushions coaxial of saidgasket, each of which permanently attaching to one of said pair ofsupport members adjacent to said outer face of one of said flanged endsand comprising at least a pair of crescent-shaped elements having commoncenters of formation defining a mean diameter about equal to that ofsaid gasket for distributing said urging pressure in circumferentialalignment with said gasket whereby bending stresses at the attachingplane of said flanged ends of said glassware sections are reduced.

7. Said joint of claim 6 in which selected openings through saidoverlapping end sections of each support member are slotted to permit,as confining pressure is removed, simultaneous radial disengagement ofsaid pair of support members and said cushions relative to saidglassware sections.

References Cited UNITED STATES PATENTS 1,309,146 7/1919 Mann 285-3681,351,573 8/1920 Hopwood 285-336 X 2,101,894 12/ 1937 Broughton 285337 XFOREIGN PATENTS 567,948 10/ 1958 Belgium.

913,374 6/ 1954 Germany.

917,219 8/1954 Germany.

773,541 4/ 1957 Great Britain.

798,305 7/1958 Great Britain.

580,911 8/1958 Italy.

CARL W. TOMLIN, Primary Examiner.

D. W. AROLA, Assistant Examiner.

1. A JOINT FOR RELEASABLY JOINING GLASSWARE MEMBERS IN FLUID-TIGHTCONTACT, COMPRISING A PAIR OF GLASSWARE SECTIONS HAVING ADJACENT FLANGEDENDS, SAID FLANGED ENDS HAVING INTERIOR ADJACENT FACES PROVIDED WITHGROOVES, AND OUTER FACES REMOTE FROM SAID INTERIOR FACES, A GASKET OFRESILIENT MATERIAL CONFINED IN SAID GROOVES, A RELEASABLE CLAMP TORELEASABLY CONFINE SAID GASKET IN SAID GROOVES UNDER SUBSTANTIALLYUNIFORM CIRCUMFERENTIAL PRESSURE, SAID CLAMP INCLUDING A PAIR OF SUPPORTMEMBERS AXIALLY SPACED APART ADJACENT TO SAID OUTER FACES OF SAIDFLANGED ENDS, CONNECTING MEANS OPERATIVELY ENGAGED BETWEEN SAID SUPPORTMEMBERS FOR AXIALLY URGING SAID SUPPORT MEMBERS INTO CONTACT WITH SAIDOUTER FACES OF SAID FLANGED ENDS TO CONFINE SAID GASKET, AND A PAIR OFRESILIENT CUSHIONS COAXIAL OF SAID